Does anyone have more information on the alleged Cornish connection? I can only offer a bit of anecdotal evidence, but for what it's worth, here it is.

During the summer of 1962 I hitch-hiked down to Cornwall with a couple of other reprobates,intending to try our luck at busking. Along the way we stopped off at Cyril Tawney's folk club at the West Hoe Hortel, and did a floor spot there. On hearing that we had nowhere to stay that night, Cyril generously allowed us to unroll our sleeping bags on his living room floor. He also advised us that "The Sweet Nightingale" always went down well with Cornish audiences, because it was considered to be 'a local song'.

I also seem to recall that Peter Kennedy's anthology of traditional songs from these islands includes a version of Sweet Nightingale in the Cornish language, though I suspect that it's a modern translation.

Anyone out there from Mebyon Kernow with more information?

Wassail!